In order to operate a radio telecommunication network efficiently, the coverage area and service quality of the network have to be continuously monitored and the network configuration should be modified if network performance is inadequate. Before any modifications of the network configuration are deployed, the potential impact of those modifications on network coverage and performance should be assessed.
Typically, any modifications to the network configuration are first evaluated (e.g., with tools such as a TEMS Cell Planner), and then are implemented if approved by the evaluation. An engineering team verifies deployment of the modifications using drive tests, and tunes the modifications if necessary. One example of such network configuration modifications may include turning off some selected cells in the network (e.g., during low traffic hours, such as at night) so that the network coverage is not negatively affected. Before a network operator executes such a modification, he/she may want to verify that network coverage will be maintained even after the selected cells are turned off.
In today's radio networks, one or more systems collect and evaluate network field strength measurements from user equipment (UE) (e.g., mobile communication devices) in order to map coverage and performance capabilities of the network. For example, a Long Term Evolution (LTE)-based network can request UEs to perform reference symbol (RS) measurements periodically and to send the RS measurements to the LTE-based network. The LTE-based network can collect RS measurements, and can associate the collected RS measurements with UE location (e.g., if a mobile positioning subsystem is available).
Newer generations of radio networks are expected to adapt to timely and spatially varying network traffic demand, in a much shorter timescale (e.g., from hour-to-hour) than existing radio networks, and with no or minimal network operator intervention. A network with such features could, for example, concentrate radio resources at hot spots or could turn off unutilized network resources when there is no demand for them.
Since any modification to a correctly operating radio network involves the risk of losing network coverage or degrading network performance, network operators are reluctant to frequently tune network configuration parameters, such as antenna tilt or base station power level. Furthermore, verifying the deployment by drive tests is a tedious and costly task if such network configuration modifications occur frequently. Currently, network operators rely on predictions obtained by repeating a cell planning procedure. However, the cell planning procedure requires human interaction (e.g., making it a slow alternative) and is not applicable to an automatically running self-organizing network (SON) mechanism.
One alternative approach to drive tests includes using existing UE measurements to collect information about network coverage areas and assessing an expected impact of network reconfigurations based on these measurements. One important challenge with this approach, however, is the creation of measurement conditions in an initial network configuration so that the measurement conditions are as similar as possible to hypothetical conditions that would be seen in a reconfigured network. Thus, the creation of measurement conditions for the hypothetical network configuration is important in order to accurately predict the impact of a particular network reconfiguration. More specifically, it is particularly challenging for UEs to take neighbor cell measurements during a high interference situation, especially in a single reuse frequency radio network (e.g., a single-carrier Wavelength Code Division Multiple Access (WCDMA) network or a LTE network). The measurements on weaker signals are inaccurate or impossible to measure if a serving signal is a magnitude larger. This makes it particularly difficult to estimate the hypothetical coverage from a neighbor cell while being in the coverage area of another cell.